Washington - Retiring U.S. Sen. Joe Lieberman, D-Conn., made a passionate plea for bipartisanship in his farewell speech on the floor of the Senate Wednesday afternoon, while reflecting on the changes in the chamber since he was first sworn in nearly a quarter of a century ago.

"Today I regret to say, as I leave the Senate, that the greatest obstacle that I see standing between us and the brighter American future we all want is right here in Washington," said Lieberman, bemoaning polarization and what he called the lack of compromise.

Lieberman - known for reaching across the political aisle on issues of foreign policy and national security - appealed to the 12 incoming senators elected on Nov. 6 to help change the atmosphere in Congress.

"I know how hard each of you has worked to get elected to the United States Senate," Lieberman said. "There is no magic or mystery about the way to (make a difference) in the U.S. Senate. It requires reaching across the aisle and finding partners from the opposite party. It means ultimately putting the interests of country and constituents ahead of the dictates of party and ideology."

It was, in effect, a defense of the sometimes lonely path that Lieberman has chosen to follow since his 1988 election to the Senate.

A lifelong Democrat who was his party's vice presidential nominee in 2000, Lieberman later broke with his many members of his party over his support of the Iraq War in the early part of the last decade. It led to his defeat in Connecticut's Democratic Senate primary in 2006, but Lieberman nonetheless won re-election that November when he ran as an independent.

He further infuriated many fellow Democrats by supporting Republican John McCain over Democrat Barack Obama in the 2008 presidential election, including delivering a speech at that year's Republican National Convention. In fact, McCain, the senior senator from Arizona and now one of Lieberman's closest allies in the Senate, crossed the aisle Wednesday to give his "friend from Connecticut" a hug at the end of his speech.

Senate Majority Leader Harry Reid, D-Nev., who resisted pressure from some within his party to strip Lieberman of his committee chairmanship following the endorsement of McCain, paid tribute to the retiring senator on the floor Wednesday.

"Although we have so much in common, Sen. Lieberman and I don't always agree," Reid acknowledged wryly. "But regardless of our differences, I have never doubted Joe Lieberman's principles or his patriotism. And I respect his independent streak, as it stems from strong convictions."

Lieberman also reflected on his long career in the Senate, noting that it had begun at a time when "a blackberry was a fruit and tweeting was something only birds did."

As the chairman of the Homeland Security and Governmental Affairs Committee, Lieberman considers creation of the 9/11 Commission and Department of Homeland Security among his greatest achievements. He urged his colleagues to continue his legacy of giving priority to national security issues.

"None of the challenges we face today in a still dangerous world is beyond our ability to meet," he said. "Just as we ended the ethnic cleansing in the Balkans, we can stop the slaughter in Syria. Just as we nurtured the democratic transitions after communism fell in central and eastern Europe, we can support the forces of freedom in the Middle East today."

Lieberman also cited some of the domestic changes that the country has undergone during his time in the Senate.

"Barriers of discrimination and bigotry that just a few decades ago seemed immovable have been broken, and doors of opportunity have been opened wider for all Americans, regardless of race, religion, gender, ethnicity, sexual orientation, age or disability," he said.

Lieberman worked with a coalition of Democratic senators to repeal "Don't Ask, Don't Tell" - the ban on openly gay men and lesbians serving in the military- in late 2010. The senator also broke some barriers himself. As he noted in his farewell speech, in 2000, he became the first Jewish-American nominated by a major political party for national office.

Lieberman ended his comments on a personal note, recalling the time he spent as an intern for the late Sen. Abraham Ribicoff, D-Conn., longing to return to the building someday as a senator himself.

"Well, I have been blessed to live that dream, and that is what America is all about," he said.